Abrasive jet cutting machines are used in many industries for machining various types of products and materials. An abrasive jet cutting machine mixes abrasive material, such as garnet, with high pressure fluid (e.g., water) flowing at a high rate of speed. After a machining operation, the abrasive fluid typically accumulates in a catcher tank where the abrasive material settles to the bottom. Over time, the amount of abrasive material in the catcher tank builds up and must be removed. Removing the abrasive material by conventional methods such as manual shoveling or vacuum suction typically involves shutting the jet cutting machine down, which may be economically undesirable.
U.S. Pat. Nos. 4,872,975 (the '975 patent) and 5,979,663 (the '663 patent) describe methods for continuously separating and recovering abrasive material without requiring that the jet cutting equipment be shut down. The method proposed by the '975 patent involves separating abrasive material from a slurry via a centrifugal pump and settling tank. The centrifugal pump separates some of the abrasive from the slurry via centrifugal force and the settling tank is used to separate the remaining abrasive material. Unfortunately, centrifugal pumps are generally not recognized as being reliable when handling abrasive materials. Centrifugal pumps may be susceptible to wear and clogging in the presence of abrasive materials, which may require significant and costly maintenance.
The '663 patent describes a method for recovering garnet using a diaphragm pump and coarse filter. Although generally recognized as being more effective at handling solids than centrifugal pumps, diaphragm pumps may also be susceptible to wear and clogging in the presence of abrasive material, which may require significant and costly maintenance.
International Patent Application Nos. WO 99/55492 and WO 01/14102 describe respective methods of using gas bubbles injected into an arrangement of conduits to move a slurry mixture of garnet and water into a settling container. Unfortunately, the proposed arrangements of conduits is somewhat complex, and utilizes multiple horizontal runs and elbows which can become obstructed with abrasive material. Typically, a back-flushing operation is required to remove clogs from the conduit.
The principal of using compressed air bubbles to lift water from a well or other source is well documented (e.g., see Section 4—4 of US Army Field Manual FM 5-484 dated Mar. 8, 1994).